1. Field of the Invention
The embodiments discussed herein are directed to a power supply voltage supply circuit and a disk apparatus. More specifically, the present invention relates to the power supply voltage supply circuit for supplying a power supply voltage to data input-output unit transmitting data with data processing unit, and to the disk apparatus having the power supply voltage supply circuit.
2. Description of the Related Art
Magnetic recording apparatuses such as hard disk drives (hereinafter referred to as “HDDs”) have been used as external magnetic recording apparatuses for computers or for consumer-use video recording apparatuses. The present HDDs are required by users to be capable of processing and storing large amounts of information such as motion pictures at higher speeds and at lower costs.
A system-on-chip (SoC) incorporated in the HDD has a read-write channel. The read-write channel executes signal processing, such as modulating data to be written onto a disk medium with a magnetic head into codes and outputting the data to a head IC, and detecting signals from waveforms read from the disk medium, in other words, demodulating data from signal codes output from the head IC.
Currently, the HDDs are incorporated in portable electronic devices and used in a mobile environment, or connected with personal computers via USB or IEEE1394 buses. For the HDDs used under such conditions, reducing power consumption is particularly expected.
A technique for operating a comparator in accordance with reproduction frequencies by adjusting the magnitude of a current has been disclosed in patent literature 1 (Japanese Unexamined Patent Application Publication No. H7-57395). With the technique, data are reproduced with both high and low frequencies to reduce power dissipation.
With the technique, the current magnitude is controlled with an analog circuit. Thus, the analog circuit becomes intricate. What's more, there has been an expectation for a new technique for reducing the power consumption not only in writing but also in reading.
The power supply voltage supply circuit and the disk apparatus according to this embodiment of the present invention are disclosed to solve the problems described above. An object of the present invention is to provide a power supply voltage supply circuit and a disk apparatus that are capable of reducing power consumption in data writing and reading.